This invention relates to the polymerization of olefins to produce longer chained olefin products. In a further aspect, the invention relates to the production of olefins and alkylbenzenes which are especially useful as intermediates in the production of alkylbenzene sulfonate detergents. The invention also relates to such detergents and their production.
One significant commercial application of longer chained olefins (e.g., C.sub.10 to C.sub.15) is as intermediates in the production of alkyl aromatic sulfonate detergents. Since large amounts of such detergents are ultimately released to the environment, the need for biodegradability is well recognized. It is further well recognized that linear and mono-branched alkyl aromatic sulfonates are generally much more readily biodegraded than multibranched alkyl aromatic sulfonates and, hence, much more desirable as detergents. Thus, the need for processes which efficiently produce high yields of C.sub.10 -C.sub.15 linear or semi-linear olefins or olefin mixtures which afford biodegradable alkylbenzene sulfonates.
U.S. Pat. No. 3,315,009 discloses a two-dimerization step process for preparing C.sub.8 -C.sub.16 olefins using a heterogeneous cobalt oxide catalyst. Patentee teaches that it is preferred that the dimer feed to the second stage dimerization be substantially linear, but that the presence of branched-chain mono-olefins in the feed to the second stage up to 15% by weight is not deleterious.
U.S. Pat. No. 3,317,628 discloses a two-dimerization step process for preparing higher olefins similar to that described in the aforementioned patent, but using a somewhat different heterogeneous cobalt catalyst. Patentee stresses one of the advantages of patentee's process is that the formation of undesired isomers, such as 2-methylpent-2-ene is minimized if not eliminated. Patentee describes 2-methylpent-2-ene as an especially undesirable isomer in hexene fractions for the purpose of patentee's process because it is not separated from n-hexene by commercial methods of distillation and therefore requires special separation procedures or it must remain as an impurity.
U.S. Pat. No. 3,402,217 discloses a two zone polymerization process for preparing higher olefins using a molecular sieve or zeolite catalyst. Patentee teaches that a particularly preferred mono-olefin dimer feed to the second zone polymerization is one which contains no greater than 10% by weight of branched-chain mono-olefins and the remainder straight-chain mono-olefins. Patentee further teaches that generally ordinary fractional distillation is adequate to purify the first dimerization zone product, but that in addition to or in place of fractional distillation, other conventional separation or purification means such as adsorbents, i.e., molecular sieves, solvent extraction, extractive distillation, selective polymerization, isomerization, and the like may be employed to conform the dimer product of the first-stage dimerization to the feed requirements of the second-stage dimerization. Patentee states that it is immaterial to patentee's invention what separation means is used for purifying the product of the first-stage dimerization to meet the feed requirements of the second-stage dimerization, so long as such separation means provides the desired purification.
U.S. Pat. No. 3,409,703 discloses a two-dimerization step process similar to that disclosed in U.S. Pat. No. 3,315,009, but using a modifying agent in the first dimerization.
The recovery of isobutylene from C-4 hydrocarbon streams is reportedly disclosed in Belgium Patent No. 851,832; Japanese Patent Application No. 49061102; Chem. Abstracts, Vol. 83-179515; and Khim Prom, Vol. 41, No. 8, 625-26 (August 1965).
U.S. Pat. No. 3,424,815 describes the preparation of alpha-olefin oligomers using a catalyst comprising the product of certain nickel chelates with a halide-free organoaluminum compound such as alkyl aluminum alkoxides. Patentee teaches that the nickel chelating ligand-anion is substituted with electron withdrawing groups, i.e., nitro, halo, cyano or carboalkoxy and that superior results are obtained when the chelating ligands are halogenated organic ligands.
U.S. Pat. No. 3,592,870 discloses olefin dimerization process using a catalyst formed from an organoaluminum compound and one of the following nickel complexes: (a) bis(beta-mercaptoethylamine)nickel (II) complex; (b) alpha-diketobis(beta-mercaptoethylimine)nickel (II) complex; (c) S,S,-disubstituted bis(beta-mercaptoethylamine)nickel (II) complex; or (d) S,S,-disubstituted-alpha-diketone bis(beta-mercaptoethylimine)nickel (II) complex. Based on the product distribution shown in the examples of this patent, the polymerization of propylene using patentee's catalysts C.sub.6 olefin products containing 63 to 70% branched olefins depending on the particular catalyst used.
U.S. Pat. No. 4,069,273 describes a process for dimerizing low molecular weight linear alpha-olefins using a complex of bis(1,5-cyclooctadiene)nickel and hexafluoro-2,4-pentanedione as a homogeneous catalyst. Patentee describes his process as producing a highly linear olefin product. U.S. Pat. No. 4,366,087 describes a process for oligomerizing olefins using a catalyst containing a nickel compound having the formula (R.sub.1 COO)(R.sub.2 COO)Ni, wherein R.sub.1 is a hydrocarbyl radical having at least 5 carbon atoms and R.sub.2 is a haloalkyl radical and an organic aluminum halide. As can be seen from the examples in this patent, patentee's process afforded a product containing a large amount of branched olefins. A number of catalyst systems used for the polymerization of olefins are described in Chemical Review, 86 (1986), pp. 353-399.
Although the prior art speaks in glowing terms of highly linear products, seldom are such results obtained except at the cost of low yields or other disadvantages. For example, the two-step processes of the prior art which produce highly linear C.sub.10 -C.sub.15 olefin products also generally require a highly linear intermediate product, thus effectively wasting significant yields of methyl pentenes which are obtained in the first step reaction product. The prior art systems using heterogeneous catalysts suffer from the usual contact problems incident to such catalysts. Moreover, the heterogeneous catalysts used by the prior art are frequently difficult and expensive to prepare. The use of halide modifying agents also presents a problem since such agents are generally very corrosive and presents equipment problems.
Thus, there is a need for better processes for producing detergent grade C.sub.10 -C.sub.16 olefins.